The White-necked Jacobin, scientifically known as Florisuga mellivora, is a medium-sized hummingbird adorned with a striking plumage. The male is particularly distinctive, boasting a dark blue head and chest, contrasted by a pure white belly and tail, the latter tipped with black. A white band graces the nape, setting apart the blue head from the vibrant green back and elongated uppertail coverts. Females exhibit a more variable appearance, often showing green upperparts and a blue-green throat, with white "scales" and a white belly. Their tails are mostly green with a blue terminal band.
Males are unmistakable with their contrasting blue and white plumage. Females and immatures can be more challenging to identify due to their variability, but typically females have less white in the tail and a bronzy hue on the throat and chest.
This species is found in the canopy and edges of humid forests, as well as in semi-open areas like tall secondary forests, gallery forests, and plantations of coffee and cacao. It tends to stay high in the trees but may descend to lower levels at forest edges and clearings.
The White-necked Jacobin ranges from Mexico through Central America and into northern South America, including Brazil, Peru, and Bolivia. It is also present in Trinidad & Tobago. The nominate subspecies, F. m. mellivora, is widespread, while F. m. flabellifera is endemic to the island of Tobago.
This hummingbird's movement patterns are not fully understood, but it seems to shift seasonally in response to flowering patterns. It is known to be aggressive towards conspecifics when feeding but is not typically territorial.
The White-necked Jacobin is not a particularly vocal species. Its song consists of a series of high-pitched notes, while its calls include a short 'tsik', a high-pitched 'sweet', and a descending 'swee-swee-swee-swee' during antagonistic interactions.
Breeding occurs during the dry to early wet seasons, with timing varying across its range. The nest is a shallow cup made of plant down and cobwebs, often situated on a leaf and sheltered by another leaf overhead. Males engage in display flights and chases, while females perform fluttering flights to distract predators.
The diet consists primarily of nectar from flowers of tall trees, epiphytes, shrubs, and Heliconia plants. They are also insectivorous, hawking small insects through various aerial maneuvers.
The IUCN has classified the White-necked Jacobin as Least Concern due to its extremely large range. While the population size is not quantified, and trends are unknown, the species is considered uncommon to common throughout its range and is able to adapt to human-modified habitats.